Syringes commonly used in various application areas do not utilize a more precise dosing function beyond the grading in milliliter that normally is present on the barrel of the syringe. The dose provided by the person pressing the plunger is therefore not precise and is influenced by the skill of the user. In some application areas a precise and accurate dose is important and will in cases of various treatments of diseases increase the therapeutic accuracy, safety and efficacy of the treatment. In areas where a diagnostic application is used, such as in vitro or in vivo testing, exemplified by patch testing in contact dermatitis, an accurate and quantified dose will provide a higher accuracy and validity of the method. In this diagnostic procedure a dose of a hapten (test preparation) is applied onto a test chamber mounted on a strip of tape that is subsequently applied onto the patients back. The dose that is applied using a graded syringe is not precise and may vary by a factor of at least 1 to 3 using current techniques. Achieving a precise dose will not only result in an increased accuracy of the method in individual patient investigations but will also result in a higher validity in coordinated clinical multicenter studies as the elicitation and intensity of the clinical immunological reaction is dependant on the dose given. The results in the different clinics can therefore be accurately compared as the same dispensing volume is applied. Similarly it is important when administering certain medications to a patient that the volume is known so that the patient is safely treated without risk for overdosage of the medication resulting in adverse side effects and serious medical conditions or underdosage resulting in lack of achieved effect. Likewise, when administering dental materials it is of importance to provide a predetermined controlled dose in order to give the patient an accurate treatment. Accordingly, the unsatisfying accuracy of the syringes used today constitutes a problem when used in situations as mentioned above.
Previous inventions have not been able to teach an inexpensive, easy to use, prefilled or unfilled syringe that allows the physician or other user to accurately dispense a quantified volume of sterile or unsterile, viscous or non-viscous material by using a screwable syringe device dispensing material via a rotational movement of the plunger. A few attempts have been made to provide some of these desired features by way of combining special metering devices with the conventional syringe and other attempts have required the conventional syringe cylinder to be modified. Unfortunately, the ability to dispense a controlled calibrated dose of a material by using such a mode of action has not been successful.
Another drawback of the present dispensing technique using a syringe with a traditional plunger and barrel is in the ergonomical area. After some time, a nurse or other personnel using today's technique may develop pain in the thumb and hand due to the repeated pressing of the plunger and wear may also occur resulting in absence from work and sick leave due to this kind of work related disease.